1. Field of the Invention
The present invention relates to a CMOS transconductance amplifier comprising a voltage-to-current converter having a differential input for an input voltage, and further comprising an output current mirror having its control input coupled to the current output of the voltage-to-current converter, with the high-impedance current output of the output current mirror connected to an output node from which the output current of the transconductance amplifier, load current, is obtainable.
2. Description of the Related Art
High-transconductance amplifiers are also referred to as "operational transconductance amplifiers." They are used as amplifying elements for switched-capacitor filters and should have as high a gain as possible. By the high transconductance, the respective charge condition of these capacitors is to be brought to a new charge condition as quickly as possible. The stability of this recharging process is ensured by the load capacitance itself.
One disadvantage of CMOS monolithic integrated transconductance amplifiers is the relatively low transconductance of the MOS transistors. Another disadvantage results if MOS transistors are used in such amplifiers as source followers because these source followers have a relatively high internal resistance. Furthermore, with the wide variation in load current, which results from the capacitor recharging, the square-law current-voltage characteristic enters into the recharging process during large-signal operation, which produces distortion with an even harmonic component.